The invention relates generally to portable digital audio play-out devices. More particularly, it concerns the provision of high-quality, high-volume digital audio file format compatible with downloading music to a portable hand-hand held device. Even more particularly, it concerns the so-called ‘swarm’ or ad-hoc networking of physically proximate portable hand-held MIDI music devices for real-time peer-to-peer musical jamming or music-sharing.
Portable MP3 players such as the Intel PocketConcert™ player provide a convenient way to transport music while traveling. However, even the best-known methods of audio compression, e.g. MP3, still produce extremely large files. For example, an hour of music compressed to 128 kilobits/sec (kbps) with MP3 occupies approximately 64 megabytes (MB) of memory. Such a large memory requirement limits range of access to portable music and for many is prohibitively expensive.
PCM audio, e.g. audio CDs or WAV files, are created by sampling a continuous audio signal and recording the amplitude in digital form. Those of skill in the art will appreciate that such a recording format is very data intensive and requires very high-bandwidth (e.g. 1.2 megabits/second (1.2 Mbps) data input/output (I/O) and data processing pathways and proportionately very high-capacity memory storage.
Conventional portable MP3 or Windows Media players and music synthesizer programs on desktop personal computers (PCs) transform time-domain PCM signals into frequency-domain audio data and then compress the data to eliminate inaudible frequency ranges. Such compressed-audio data files nevertheless require high-bandwidth processing (e.g. 128 kbps) and proportionately high-capacity memory storage. With desktop PCs, such large memory requirements are more easily met than with hand-held portable or pocket devices such as personal digital assistants (PDAs) or so-called pocket PCs. Those of skill in the art will appreciate that, the larger the memory, the more substantial the power requirement. Thus, large memories required to store even compressed, e.g. MP3, high-fidelity music-representative data in hand-held portable devices, also decrease useful battery life, which remains at a premium despite continuous developments in battery technology.
The musical instrument digital interface (MIDI), an existing music industry standard, is a common interface option on many desktop PCs. It provides a coding standard for synthesizing and recording musical events, e.g. note on, note off, attack, delay, pan, etc. Familiarity by those of skill in the art with the MIDI standard is assumed. Generally, the MIDI format is considered a compressed format because it does not require synthesis or storage of each and every nuance of continuous voice, pitch, duration, volume and envelope quality of a musical note, beat, phrase, score or lyric. Essentially, it is represents a computerized version, or coded, musical score that defines only musical events and their sequence, thereby significantly reducing the overhead of such detailed, high-bandwidth audio sampling and recording techniques. Typically, a MIDI file requires only approximately 12 kbps in bandwidth and proportionately smaller memory storage capacity.
Accordingly, wider access to music synthesis in a convenient, portable format combined with compressed audio playback capability is desired. Moreover, real-time peer-to-peer ad-hoc ‘jamming’ or music-sharing using a plurality of physically proximate portable hand-held MIDI music devices is desired.